OK, this is a rhetorical question that deserves to be closed as "opinion based", but gotta ask. Why do we need to have "27.5 inch" bikes?

If you dig through the specs (they don't come right out and say), this is a 650B rim, which Sheldon quotes as being for "French utility bikes, tandems, and loaded-touring bikes; some older Raleigh and Schwinn mountain bikes", and which is otherwise known as 26 x 1-1/2".

  • Do you mean the size physically, or the name?
    – Vorac
    Commented Nov 11, 2013 at 17:14
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    Also, doesn't "26 x 1-1/2"" mean 26" wheel with 1.5" tire?
    – Vorac
    Commented Nov 11, 2013 at 17:15
  • 1
    @Vorac - No, "26 x 1-1/2 inches" does not mean a 26" wheel with a 1.5" tire. It means a 23 inch wheel, and the width of the tire can vary (if you can find more than one width for that diameter). And "27.5 inch" is also a 23 inch wheel. And, of course, a "27 inch" wheel is 24.8 inches in diameter, while "26 x 1-14 inches" is 23.5 inches in diameter. Does it all make sense now? Commented Nov 12, 2013 at 1:12
  • (If manufacturers would settle on about 4 standard wheel diameters for "adult" bikes the tire selection would be much better, among other things. As it is there are probably 10 sizes in "common" use, not counting "24 inch" and smaller bikes for kids. A bike shop is unlikely to carry more than one or two tires for a given size, other than 700C. At least for "29ers" they decided to use 700C rather than invent a new size or resurrect another old one.) Commented Nov 12, 2013 at 1:16

5 Answers 5


Again - Following up with an opinion from a self confessed conspiracy theorist. Its about the money - follow the profit tree to its roots

When there were only 26" wheels a small LBS needed to have one wheel set in stock, and one sized tire ( maybe 5-10 variations). They would special order specific gear the the customer wanted and could easily stock enough to supply of the shelf something suitable for most customers most of the time. The LBS had a range of MTB in stock - a few (maybe 10 bikes) would cover the requirements for 95% of his customers, and he would target a particular but broad market (Typically either Family and weekend riders, or 'cashed up cost doesn't matter wannabes and elite cyclists).

Now, the small LBS needs to stock 3 wheel sizes, in disc and rim brake style (6 wheel sets). They also need about 50 different tires on the shelve. The number of bikes required to be stocked by the LBS has also increased. He needs at least twice as many on the floor to remain competitive, but that much stock will drive him out of business. This is beyond the capability of a small LBS to do and still remain profitable. Mum and Dad now need to stock 3 different spare tire and tube sizes at home (Dads 29'er, mums 26'er and sons 27.5er').

Then there is the hype - 26'er is old, 29'er is so much better. Followed by "well, you need a 29'er for XC but AM and downhill a 26'er is better - to be a serious cyclist you have to have one of each (with spares of course). Now, we have 27.5 - So, that 29er I sold you last year really is to big, and you know that 26 so last decade, well, have I got the bike for you.... It's only $$$, but I'll throw in a discount cause you are such a valued customer.......

In effect it is being pushed by the larger retailers, who can afford the stock level, to push the small LBS out of business. The elite custom-builders where pricing is less of a concern will do very nicely out of it as well (No competing LBS focused on "reasonable pricing" will drive some people to them).

The net effect of all this choice is that the cost to us will skyrocket as the competition is shut down. We won't have competing LBS that offer personal service (except those that provide for the high end market) and will have to deal with the large, impersonal chain stores. The idea of talking to the mechanic will be seen as quaint, as the salesmen run the front counter. "Why talk the the mechanic, buy a new bike.... "

I believe the changes are mostly (99.99%) profit motivated to get more bikes moving from shop shelves to unused garage ornaments.

  • 2
    Why every bike requires a different (and expensive) derailler hanger? It's too difficult to have a few standard sizes?
    – user5369
    Commented Nov 11, 2013 at 10:03
  • Of course in reality there were already a bunch of different "26-inch" tire/rim sizes. But adding "27.5" as just another term for one of the 26" sizes is highly unhelpful. If they want a new term they should use the metric size of the rim (except that I suppose that metric measurements are equated with effete road cycling, while inch measures imply "manly" off-road). Commented Nov 11, 2013 at 16:30
  • Isn't the term officially 650b?
    – Aaron
    Commented Nov 11, 2013 at 22:00
  • I've seen a lot of local bike avoid this problem by specializing on a sub-market within the bike community. In my city there are stores that focus more on road/race bikes, others focus on urban/commuter bikes, and other that focus on mountain bikes. Not only does this allow them to carry more stock, but it allows their employees to be much more knowledgeable about the products they sell, because there's a smaller range of parts. It's also much more likely that the employees are interested in what they are selling.
    – Kibbee
    Commented Nov 12, 2013 at 13:45

Having ridden some of the major wheel sizes:

  • 20 - BMX
  • 24 - Bigger BMX
  • 26 - Mountain Bike
  • 27.5 - Mountain Bike
  • 29 - Mountain Bike/Road Bike

I can honestly say it depends on what you want to do. I race XC on my 29er because it climbs way better than 26 and runs like a road bike on the flats, but it totally sucks in tight switchbacks due to the large turn radius (and long frame because I'm tall).

My Dirt Jump and All-Mountain bikes are both 26" because I can maneuver the bike a lot better. The AM bike is more on the freeride side so the components were easier to find to make it beefy for that.

I've ridden 650b on trails and found that they mix the 29er and 26er together, it climbs better than 26, but not as well as the 29. It decends better than the 29er and is certainly more playful on the trail too. However, I don't really think it's the end-all, be-all of bike wheels as I didn't jump on abadoning my other bikes.

Personally, I think it's a choice thing, where you find a bike that fits what you want to do and how you want to ride. I'd prefer that biking not become like stock car racing, where all the major pieces are the same and only the small components are different. I think that's the same reason people own two, three, or more bikes, because they don't want a bike that can do evertyhing but doesn't excel at one thing. Yeah, I can take my 150mm FS 26er on XC trails, but it really sucks in spots. Maybe the same bike with 650b size wheels would improve the pedaling parts for me, but someone else might disagree.

I like the comments about bike shops having to carry more stuff, as that's always a challenge for any distributor, but I think the brick-and-mortar shops are becoming more of showrooms nowadays anyway. Flexibility and variability really should be a good thing as it should open up more customers that may have been unhappy with the other, current options.

  • 3
    +1: I agree that for an enthusiast it make sense to have the perfect bike for each ride. The reality is a vast majority of bike owners own one bike (and don't hang out here), and a majority don't even know there are different wheel sizes, let alone what they have. For them, if the wheels go round and tires have air, its good enough.....
    – mattnz
    Commented Nov 11, 2013 at 23:42

Following up with an opinion, I believe this is simply about getting people on new bikes.

  • People are willing to stay on their frames until they're broken while doing upgrades through the likes of CRC and Wiggle which I imagine offer very low return to anyone but component companies.
  • 29er's became stale and XC focused only in the past year have people started using them on rougher stuff.

I don't think the science behind 27.5/ 650Bs make a convincing argument. Giant put a lot together to justify their move to 27.5s (glidepath to only that size in about 2016). There is a scientificish review here on PinkBike.

This article and Giants move was pulled apart on this forum on Vorb - on Vorb it takes a few posts for things to move past general mud slinging, page 2 gets pictures and analysis.

Personally I've never ridden a 27.5 (my sister has one but as it's a "girls" bike I couldn't possibly be seen on it) and my only experience on a 29er is on a FS and I found the ride too sedate compared to my steel HT.


27.5" bikes were introduced after manufacturers found out that they can not produce 29ers with optimal frame geometries for small riders.

Considering one of strong sides for 29er vs 26er - tire contact patch, 27.5er is closer to 26er, so no big gains there.

There is plenty of marketing information and very little actual research available, so one has to be really careful when reading various manufacturer claims.

  • So why not call it a 650C? (And what, pray tell, is a "26er"? Especially given that a 650C is "26 x 1-1/2"?) Commented Nov 12, 2013 at 12:31
  • It is officialy 650B, 27.5 is just a marketing name.
    – Papuass
    Commented Nov 12, 2013 at 13:29
  • So why not call it 26? Commented Nov 12, 2013 at 13:30
  • That would be confusing considering we all think of 26 inch / ISO 559mm wheels when we see 26.
    – Papuass
    Commented Nov 12, 2013 at 14:00
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    Actually, 26" is 571, 597, 590, 584, and 559mm. Calling a wheel "26 inch" is not being at all specific. What "we" think of when "we" see "26 inch" depends on who "we" are and what kind of bikes "we" ride. But I've ranted enough about my pet peeve of constantly changing bike "standards". Folks are welcome to vote this question into oblivion. Commented Nov 12, 2013 at 16:29

Firstly, 650B never really went away; Herse kept building 'em, and Sheldon advocated them as a way to get wider tyres, fenders, etc. on tight clearance 700C frames.

Secondly, a number of bicycle advocates such as Heine discovered this and started evangelising the beauty of French bicycles. (Even Sheldon himself could be considered in this group).

Thirdly, La Confrérie des 650 has been complaining for a long time about these new fangled tyre sizes like 26" (559) or 700C dominating the wheel and tyre market. Particularly 559, because it is a marketing gimmick, designed to sell through artificial product differentiation... Though they also wouldn't mind if 27.5" were less marketting, and better at specifying tyre and brake suitability.

  • So the real purpose of the 27.5" wheels is to make use of all the old 700C frame manufacturing facilities? Commented Jan 21, 2014 at 23:06
  • Sheldon's case for refurbing an 80s road bike that's too "sporty" to be a utility/tourer with 650Bs is more "make do and mend" than manufacturing. Put it this way: if I found my perfect OTS with braze ons from the 70s, I'd put 700Cs on it; if I found my perfect OTS with braze ons from the 80s, I'd put 650Bs on it. Regarding contemporary mountain bike manufacturers: its specious product differentiation to expand the market. Commented Jan 21, 2014 at 23:20

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